Send mail from inboxes Cargo owns — provision mailboxes on a sending domain, run provider warm-up and the 5→40/day send ramp, deliver with the `sendEmail` action, and read back threads, replies, delivery events, and the workspace suppression list. Triggers: "set up a sending mailbox", "provision inb

Cargo CLI — Mailbox Management Mailboxes. A mailbox is a real sending inbox the workspace owns — provisioned through Cargo on a sending domain the workspace also owns, with SMTP and IMAP credentials Cargo holds and uses to deliver outbound mail and to read the replies that come back. Two things follow, and both are easy to get wrong: a mailbox is a recurring monthly credit charge rather than a per record one, and this domain does not send. It provisions the inbox, ramps it, and reports on what it did; the send itself is the sendEmail action, under [ cargo orchestration ](../cargo orchestration/SKILL.md). Version note. Everything on this page is live in the pinned CLI (1.0.66), including mailbox get warmup stats and the daily target default of 40 — both of which were merged but unpublished when this skill was written. On an older CLI, daily target reads "provider default if omitted" and get warmup stats silently prints the mailbox group help instead of erroring , so a missing subcommand here looks like a usage mistake rather than a stale install. cargo ai mailboxManagement mailbox help lists what your CLI actually has; re run the session refresh in [ ../cargo/SKILL.md ](../cargo/SKILL.md) to catch up. Bootstrap Already signed in ( cargo ai whoami returns a workspace)? Skip to the next section. Every command prints JSON to stdout; failures exit non zero with {"errorMessage": "..."} . Nothing in this domain is asynchronous — every command is a single HTTP call, so there is no run to poll (the one thing that looks async, a freshly created mailbox sitting at pending , is polled with mailbox refresh status , not with run get ). Mailboxes are guarded by mailboxManagement:read / mailboxManagement:write permissions, which an admin and an editor both hold and a viewer does not; if a create or update returns a permission error, the token is read only ([ ../cargo workspace management/SKILL.md ](../cargo workspace management/SKILL.md)). When the full skill bundle is installed, [ ../cargo/references/prerequisites.md ](../cargo/references/prerequisites.md) adds the CLI version pin, token scopes, and the admin only surface. Before any send — three checks This is a blocking gate, not advice. Cargo owning the mailbox changes who presses send; it changes nothing about whether the message should be sent. The canonical rules are [ ../cargo gtm/references/acceptable use.md ](../cargo gtm/references/acceptable use.md) §3 and they apply here unchanged — run all three before the first sendEmail , not after: Basis — which permission covers this audience (customers, opted in contacts, event attendees, or a documented legitimate interest case for a B2B role)? Suppression — subtract the workspace suppression list from the audience before you enrich or send. suppression list is free and this domain is the source of truth for it. Relevance — can you name, per recipient, why this message is for them? Any check that fails is a stop and ask. Two obligations are specific to Cargo owned sending: The ramp is a ceiling, not a target. get send allowance reports what a mailbox may send today; it is not a quota to fill. Asking to raise it, to spread one campaign across a fleet of fresh mailboxes to clear the same volume, or to rotate identities so filters see less from each, is the evasion refusal in acceptable use.md §2 — not a configuration question. Unsubscribes are automatic and absolute. Every send carries a signed List Unsubscribe header; a recipient using it writes a workspace wide suppression row, and the next send to that address is refused by the engine. There is no removal command, and that is the point — never route around a suppression to re contact someone. The two numbers that govern a mailbox They look similar and mean opposite things. Confusing them is the most common way to mis read a mailbox's health. mailbox get send allowance mailbox get warmup stats Measures Your real outreach The provider's dummy warm up traffic Window Rolling 24 hours Today, UTC Returns dailyLimit , sentCount , remainingCount sentCount , deliveredCount , spamCount , inboxRate , spamRate Answers "How many more may I send?" "Is this inbox landing in the inbox or in spam?" dailyLimit is not a setting — it is derived from how long warm up has been running. The arithmetic, the warmupStatus transitions, and how to size a fleet against it are in [ references/warmup and allowance.md ](references/warmup and allowance.md) . Read it before you promise anyone a send volume. Commands All commands output JSON. Reads need mailboxManagement:read ; everything that provisions, updates, deletes, or suppresses needs mailboxManagement:write . Provision a mailbox First, the gap you will hit. mailbox create requires domain uuid , and there is no cargo ai command that lists sending domains — the domainManagement API exists but has no CLI surface yet. Get the UUID from the Cargo web app, or declare the domain in a CDK repo with defineDomain and read it back from cargo.state.json . Say this to the user rather than guessing a UUID. type — google , shared , or private . outlook is accepted by the flag and always fails with transportNotSupported : the Graph transport has not shipped, so an Outlook mailbox cannot deliver. Pick one of the other three. username — the local part only ( jane for jane@acme.com ). Lowercased; letters, digits, dots, dashes and underscores, 1–64 characters, starting and ending alphanumeric. first name / last name — the From header the recipient sees. Use a real person's name under a real identity; a fabricated sender is a §2 refusal. signature — HTML, stored on the mailbox (max 10,000 characters). folder uuid — a folder of kind mailbox , from [ cargo workspace management ](../cargo workspace management/SKILL.md). create returns immediately with status: "pending" — the provider has not issued credentials yet. It reaches active when refresh status says so, or on its own within five minutes; a send attempted before then fails with credentialsMissing . statuses — pending , active , inactive , comma separated with no spaces . An inactive mailbox was disabled by the provider; errorCode says why ( 401 auth, 402 spam) and it will not send until it is fixed. none is the sentinel for "clear it" on folder uuid and signature . On list , folder uuid none means "mailboxes in no folder". remove is how monthly billing stops. There is no pause. Warm it up A mailbox that never starts warm up is pinned at 5 real sends a day, forever . Warm up is what moves it, and it takes 45 days to finish. daily target — warm up messages per day at full ramp, 1–40 (default 40). This is the provider's dummy traffic, not your send allowance. status on update warmup accepts the whole enum, but only active and paused do anything: pending and failed are states the provider reaches on its own, and disabled is what stop warmup is for. stop warmup resets the Cargo send ramp as well as tearing down provider warm up — the mailbox drops back to 5/day and starts the 45 days over. Pause instead unless you mean it. Check the allowance before you send Read remainingCount before enrolling a batch. Sends past it do not queue for tomorrow — they fail immediately with dailyLimitReached , one wasted run per row. Read what happened Message vs thread vs event. A message is one outbound send. A thread is a conversation — its lastEmail and lastEvent are what you sort a reply queue on. An event is something that happened to a message ( sent , opened , clicked , replied , bounced , unsubscribed ). Inbound replies are events, not message rows; only outbound mail is a message. statuses on message list / thread list is the list status — pending , error , or an event kind. success is not in that set: a delivered message reads as sent or later. kinds , statuses , reasons are all comma separated with no spaces. bounced never fires yet. Nothing parses delivery status notifications, so bounces do not produce events and do not auto suppress. Do not build a deliverability report that treats an empty bounce count as a clean list. message , thread , and event lists default to limit 50 (max 200) and return a count . mailbox list and suppression list have no default limit (max 1000), and mailbox list returns no count — see [ references/response shapes.md ](references/response shapes.md). Suppression Workspace wide, not per mailbox: a recipient opting out is opting out of the sender, not of one address the sender happens to own. Reasons are unsubscribed (the recipient's own choice, via List Unsubscribe ), bounced , complained , and manual . suppression create always records manual . It is idempotent — suppressing an already suppressed address returns the existing row. Addresses are normalised ( trim().toLowerCase() ) on both write and check, so casing and stray whitespace cannot slip a suppressed recipient back into a send. There is no suppression remove . That is deliberate. Pricing Read this live before quoting a fleet cost — the figures above are what the workspace returned at the time of writing, not a constant. Sending: the sendEmail action Delivery is deliberately not in this CLI domain. It is a native orchestration action so that sends inherit orchestration's pacing, retry, and credit machinery: 0.1 credits per send , fixed. The action carries no config ; the inputs go in data , like every other action ([ ../cargo orchestration/SKILL.md ](../cargo orchestration/SKILL.md)). Optional bodyText (generated from the HTML when omitted), inReplyTo , and references . To keep a reply threaded, send the whole chain. references is every Message ID in the thread so far, oldest first — not just the parent. Mail clients break the thread otherwise. The action is rate limited per mailbox to that mailbox's own daily limit, spread across the day. A burst of 100 on a mailbox with 40 left fails the 41st immediately rather than parking it for a day. A refused send is a node error, not a thrown exception. recipientSuppressed , mailboxNotActive , and transportNotSupported need a human and do not retry; dailyLimitReached , credentialsMissing , and deliveryFailed retry on their own. There is no dry run from the CLI. The engine has one, but no action execute flag reaches it — the send is live the moment you run the command. Send to yourself first. Threading, the full refusal table, and what Cargo injects into every message (unsubscribe header, open pixel, click redirect) are in [ references/sending.md ](references/sending.md) . Cost discipline This domain bills differently from the rest of the pack, and the difference is the thing to say out loud before provisioning anything. A mailbox is a monthly, recurring charge — 100–160 credits per mailbox, per month , for as long as it exists. Five mailboxes is 500–625 credits every month, not once. mailbox remove is the only way to stop it; there is no pause. Quote the fleet size and the monthly credit estimate from a live pricing get , and get an explicit yes, before the first create . Sends are 0.1 each , so volume is cheap and the fleet is not. Do the arithmetic in that order. A play or scheduled tool that calls sendEmail re bills on every run — and re contacts the same people on every run, which is the §6 cadence gate in acceptable use.md as much as a spend gate. Check get send allowance before enrolling a batch: rows past the allowance burn a run each and deliver

cargo-mailbox-management